Subject:
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A practical lead screw
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Newsgroups:
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lugnet.robotics
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Date:
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Thu, 19 Aug 1999 16:57:10 GMT
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Original-From:
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John Barnes <BARNES@stopspamSENSORS.COM>
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Viewed:
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633 times
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I have finally managed to construct a workable lead screw.
I used nylon threaded rod obtainable from McMaster-Carr:
Part #: 98831A411 2 feet length of 10-32 nylon threaded rod $2.56
www.mcmaster.com
I cut this into suitable lengths equivalent to standard axle lengths.
I then used a dremel tool with a fine router bit to cut four small
segments out of 1/2" of each end to allow the rod to mate with lego
wheels and couplers. (You will have to use a magnifying glass and
an xacto knife to tidy up the threads after this.)
Then take a 1x2 brick with a hole through it and use the dremel to
remove all the inside material.
Then take a 10-32 brass nut and cut off one flat almost down to the
thread.
__
cut across here -> / \
/ () \
\ /
\__/
Insert the nut into the brick, cut side first. A little adjustment with
the dremel tool and some filing of the nut and the nut's hole will line
up with the brick's holes.
Screw the 10-32 nylon axle through the nut. You can add a small dob of
epoxy to hold the nut in place in the underneath of the brick if
necessary.
I use this in combination with another unmodified 1x2 brick with a hole
riding on a normal axle as a sliding rotation lock.
__
===========|__|========= <- normal axle
///////////|__|///////// <- lead screw
^
1x2 bricks
You can drive this directly from a motor. It is very powerful!!! If you
do not build in limit switches, it will demolish anything you install it
in, but at 32 turns/inch it offers good precision.
If you buy some nylon nuts, you'll find that they bind on the rod. This can be
very useful for creating jam nuts to limit float:
| | __ | |
//| ||////////|__|////|| |//
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^ ^ ^ ^
beam/ \ jam nuts / \ beam
I am in process of adding a web page to my home email service. I will do
real pictures then. (Sorry about the text based outlines!)
Hope this encourages those people who like to add and enhance. I know that
isn't everybody's thing, but it is so tempting!
JB
--
Did you check the web site first?: http://www.crynwr.com/lego-robotics
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